From: Andrej Bauer <Andrej.Bauer@andrej.com>
To: Angela Zhu <angela22.zhu@gmail.com>,
caml-list <caml-list@yquem.inria.fr>
Subject: Re: [Caml-list] Ocaml type with constraints?
Date: Mon, 22 Sep 2008 00:05:18 +0200 [thread overview]
Message-ID: <48D6C51E.5060901@andrej.com> (raw)
In-Reply-To: <f82e818a0809211501x824e457y164c71c9ebc45a1d@mail.gmail.com>
Angela Zhu wrote:
> Hi,
>
> I want to define an OCaml type with constraints.
> For example:
>
> type item = Item of int * float;;
>
> If here this float type is for price of some item, and I want to make sure
> it is positive. In other words, if x = (xi, xf) of type item,
> I want to enforce, xf must >= 0.
>
> Is there a way to define OCaml type like this?
No, because Ocaml type checker always check all the types at compile
time. It is an undecidable problem whether a given expression of type
float evaluates to a non-negative number.
Best regards,
Andrej
next prev parent reply other threads:[~2008-09-21 22:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-21 22:01 Angela Zhu
2008-09-21 22:05 ` Andrej Bauer [this message]
2008-09-21 23:10 ` [Caml-list] " Martin Jambon
2008-09-21 22:50 ` Gordon Henriksen
2008-09-21 23:55 ` Jacques Garrigue
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=48D6C51E.5060901@andrej.com \
--to=andrej.bauer@andrej.com \
--cc=angela22.zhu@gmail.com \
--cc=caml-list@yquem.inria.fr \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox